Nfl project report

a

1. 1
REPORT ON
INDUSTRIAL TRAINING
AT
NATIONAL FERTILIZERS LIMITED
(AN ISO-14001 UNIT)
BATHINDA




SUBMITTED BY:
KAMALPREET KAUR
UNI. ROLL NO.: 11402039
E.C.E


(10 june 2016-15 july 2016)

2. 2

PREFACE


As per the requirements of B-Tech degree course in electronics and
communication engineering vocational training has to be undertaken after
second year. To fulfill this requirement I took my training from NFL, Bathinda.
During this period everything that I learned and studied have:

The report contains all the necessary information of all the plants viz. Ammonia
plant, C.P.P., Urea plant, S.G.P. It also contains an overview of the NFL. The
information has been prepared to best of data available at that my knowledge
and time.

It is pleasure to face the industrial life that helped me to convert my theoretical
concepts into practical knowledge.

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ACKNOWLEDGEMENT



I have undergone training at NATIONAL FERTILIZERS LIMITED,
BATHINDA. During this training I have learnt a lot for which I pay my heartiest
gratitude to all the staff members of NFL Bathinda who helped me in all
respects in fulfilling my cherished desired of getting a successful industrial
training in an esteemed organization.

I am very grateful to Mr. D.K.BORA (Manager-HRD cum Head of training
Department) who deputed me with senior engineers and provided me sound
knowledge of various electronics equipments and process details. I pay my
sincere thanks to all the supervisors and the other official at the site for
providing me complete details of their respective plants..I am very thankful to
Mr.SUNIL ARORA (Head of the Electronics and communication Engineering
Department) and all the professors and lecturers of Electronics and
communication Engineering Department who guided me time to time…







KAMALPREET KAUR

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DEVELOPMENT HISTORY OF THE

ORGANIZATION



The rise in fertilizers consumption in India has been quite phenomenal
during the past three decades. To meet the rise in consumption of fertilizer ,
creation of additional capacity was also planned. The change in worldwide
energy concept and the rise in oil prices in 1973 forced India to broad base its
nitrogenous production by adopting new and sophisticated technology, which
could use cheaper sources of raw materials.

It is in this context that National Fertilizers Ltd. (A public sector
undertaking) was conceived to plan and implement two modern large capacity
single steam nitrogenous fertilizer plants in the predominant fertilizer
consuming areas of northern states in India to cater to the ever-increasing
demand for fertilizer in the region.

The company was formed and registered on 23
rd
August, 1974 to set up
two nitrogenous fertilizer plants each with a capacity of 5.115 lac tones per
annum of urea at Bathinda and Panipat.

BATHINDA was basically selected as one of the sites for this fuel oil
based plant from the consumption point of view, since Punjab with its well
organized agriculture sector, has insatiable demand for fertilizer. This combined
with excellent facilities of transport, made behind an excellent choice for this
grass root plant.

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NFL CORPORATE OBJECTIVE :

In terms of memorandum of Association, NFL was setup to manufacture
and market Chemical fertilizer, heavy water, other chemical and by products as
well as to provide the allies services.

INDUSTRY PROFILE :

The Agriculture sector is the backbone of our country. It is the most
potent factor of change that could transform the Indian economy World’ s
strongest economy.The rise in fertilizers consumption India has been quite
phenomenal during past three decades. To meet the rise in consumption of
fertilizers creation of additional capacity was also planned. The change in the
world wide energy concepts and rise in oil prices in 1973 forced India to
increase its nitrogenous production by doping new and sophisticated technology
which could use cheaper sources of new raw material.

National Fertilizers Limited (NFL) India’ s first public sector fertilizer
company was setup 23
rd
August 1974 to increase the productivity of agriculture
sector. On foundation of NFL, two nitrogenous fertilizers plant each with a
capacity of 5.11 lakhMT per annum at Bathinda and Panipat to revolutionalize
and making the era of change and excellence in Indian Agriculture sector. Both
of them were commissioned in 1979. NFL organizes a long way there after and
has emerged as one of the fastest growing company in public sector with
producing the major product as urea to make healthier the agriculture and Indian
economy. It is the second largest company in the country with an installed
production capacity of urea is 32.31 lakhT/annum within 32 years. NFL also
producing 100T of bio-fertilizer in its Indoor plant.

PRESENT SCENARIO :

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NFL has performed well during the initial six months of the current
financial year. The cumulative production of Urea during this period was 17.61
lakhT, which is 109% of the installed capacity.
Company has sold 17.77 lakhT of urea during Kharif 2005-06 against
the previous best of 16.51 lakhT. Presently, the company has the lowest urea
inventory compared to the last five years. In the first quarter of 2005-06 against
the previous best of 16.51 lakhT. Presently, the company has the lowest urea
inventory compared to the last five years. In the first quarter of 2005-06
company’ s produced 8.46 lakhT of urea recording a capacity of utilization of
104.8%. With this, the company recorded a profit before tax of Rs.22.45 Crores.
The demand during Kharif 2005 has lead to a sale of 3.07 lakhT of urea.

PAST PERFORMANCE:

In the year 2004-05 the company has achieved superb production
performance by producing 34.72lakhT of urea recording a capacity utilization of
106.2%. All the plants of the company have recorded more than 10% capacity
utilization. There is 89% of increase in company’ s net profit. The company has
also done well in production of Bio-fertilizers by producing 124T this year
against the installed capacity of 100T. The sales of industrial products also
touched new height at Rs.114.54Crores compared to 105.08Crores last year.
Company made record dispatches of 35.24lakhT of urea

FUTURE SCENARIO:

Neem coated urea has brought good results for the company. After this
success company developed a new product that is Zincated urea. The company
developed three grades of Zincated urea containing 0.5%, 1.0% and 2% have
started its trial production at Nangal unit. Furthering its innovation plans, the
company has also undertaken a project for developing the manufacturing
technique of sulphur-coated urea.

F.Y 2004-05 (NFL):

 Production 34.32LakhT/Annum
 Sales of urea 34.73LakhT/Annum
 Net profit 160.88 million Rs.
 Capacity utilization 106.2%

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PRODUCTS OF NFL:

National Fertilizer is producing “ Kisan Urea, Kisan Khad and Ankur” on
commercial scale. NFL is also marketing number of industrial products as by-
products during the formation of “ Kisan Urea, Kisan Khad and Ankur” in its
plant itself.

FERTILIZERS PRODUCTS:

 Kisan Urea
 Kisan Khad

BY-PRODUCTS:

 Nitric Acid(HNO3)
 Sulphur (S)
 Anhydrous Ammonia (NH3)
 Ammonium Nitrate (NH4NO3)
 Methonal (CH3OH)
 Nitrogen (N2)
 Carbon Dioxide (CO2)
 Sodium Nitrate
 Oxygen (O2)

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 Carbon (C) from slurry



















REQUIREMENTS OF RAW MATERIAL/INPUTS


FUEL OIL/LHLS 850 MT/DAY:

 Coal 1680 MT/Day
 Water 13 MGD
 Power 28 MW

PROJECT’ S BENEFITS:

 Increased Food Output
 Employment to nearly 6000 persons
 Both Central and State Government has been benefited by way of excise
duties and other local taxes on raw materials and other products.
 Scope for marketing by-products such as Sulphur, CO2, Nitrogen,
Oxygen, Carbon etc.

SALIENT FEATURES OF THE PROJECT:

 Annual consumption of fuel oil (raw material) 260,000 tones

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 Annual consumption of coal 320,000 tones
 Water requirement 4125 million gallons
 Power requirement 35 MVA
 Annual nitrogen capacity 236,000 tones
 Total direct employment 1200 Nos.
 Expected indirect employment 6000 Nos.
 Estimated cost of project 188.48 Cr
 Foreign exchange savings 120 Cr













BASIC PROCESS:

Urea is in many ways the most convenient form for fixed nitrogen. It has
the highest nitrogen content available in solid fertilizer (46%). Urea can be
considered the amide of carbonic acid (NHCOOH) or the diamides of carbonic
acid {CO(OH)}. At room temperature urea is color less, odourless and tasteless.
In the year heating ammonia carbonate in a sealed tube reduced 1870 urea.

Commercially urea is produced by the direct de-hydration of ammoinium
carbonate (NHCOONH) at elevated temperature and pressure. Ammonium
carbonate is obtained by direct reaction of ammonia and carbon dioxide. The
two reactions are usually carried out simultaneously in high pressure reactor.
Recently urea has been used commercial as castle feed supplement. Urea is
classified as the non-toxic compound, when urea is dissolved in water, it
hydrolyses very slowly to ammonium carbonate and eventually decomposes to
ammonia and carbon dioxide. This reaction is the basis for the use of urea as
fertilizer.

The process sequence starts with the partial oxidation of fuel oil in
standard shell reactor at 55-kg/cm² pressure followed by waste heat recovery,
steam generation and carbon removal. The raw then goes to sulphur removal
where cold methanol at about -20ºC to -35ºC washes both the organic and

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inorganic sulphur. Sulphur free gas is then led to the high temperature shift
conversion section where carbon monoxide is converted into carbon dioxide and
hydrogen. Again cold methanol at 20ºC to -60ºC is given to remove carbon
dioxide. The carbon dioxide and sulphur compounds are removed from the rich
methanol solution, which is regenerated and recycled. The gas is then passed to
the nitrogen wash cold box where liquid nitrogen wash removes the remaining
carbon monoxide and other impurities. Further nitrogen gas is added to adjust
the synthesis gas composition. The gas then goes to the centrifugal compressor
and is delivered to the synthesis reactor at the pressure of the 231 atm. The daily
output of ammonia is 900 tones. Ammonia is fed to the urea plant, where it is
reacted with the recovered carbon dioxide at a pressure of about 250 atm. The
urea solution is separated at the top of a prilling tower and collected at the
bottom in form of small particles, which is sent to bagging plant and dispatched.
The carbonate is decomposed and recycled back to the urea reactor.










INSTRUMENTS USED IN THE FIELD FOR MEASUREMENT


TRANSDUCERS:

It is a device which converts one form of energy into another form i.e. the
given non-electrical energy is converted into an electrical energy.

TRANSDUCERS USED FOR PRESSURE MEASUREMENTS:

 Absolute pressure sensor
This sensor measures the pressure relative to perfect vacuum
 Gauge pressure sensor
This sensor measures the pressure relative to atmospheric pressure. E.g tire
pressure gauge.

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 Vacuum pressure sensor
It measures pressures below atmospheric pressure, showing the difference
between that low pressure and atmospheric pressure (i.e. negative gauge
pressure), but it may also be used to describe a sensor that measures low
pressure relative to perfect vacuum (i.e. absolute pressure).
 Differential pressure sensor
This sensor measures the difference between two pressures, one connected to
each side of the sensor.

TRANSDUCERS USED FOR LEVEL MEASUREMENTS:
 Non-Contact Ultrasonic Sensors
These sensors incorporate an analog signal processor, a microprocessor, binary
coded decimal (BCD) range switches, and an output driver circuit.
 Contact Ultrasonic Sensors
A low-energy ultrasonic device within these sensors measures liquid level at
a certain point.
 Capacitance Level Sensors
Like ultrasonic sensors, capacitance sensors can handle point or continuous level
measurement. They use a probe to monitor liquid level changes.

TRANSDUCERS USED FOR FLOW MEASUREMENTS:

 Turbine flow meter
The turbine flow meter (better described as an axial turbine) translates the
mechanical action of the turbine rotating in the liquid flow around an axis into a
user-readable rate of flow (gpm, lpm, etc.)
 Thermal mass flow meters

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Thermal mass flow meters generally use combinations of heated elements and
temperature sensors to measure the difference between static and flowing heat
transfer to a fluid.

TRANSDUCERS USED FOR TEMPERATURE

MEASUREMENTS:

 Thermocouple

A thermocouple is a junction formed from two dissimilar metals. Actually, it is
a pair of junctions. One at a reference temperature (like 0 oC) and the other
junction at the temperature to be measured. A temperature difference will cause
a voltage to be developed that is temperature dependent.


 Resistance temperature detectors (RTDs)

Resistance thermometers, also called resistance temperature detectors
(RTDs), are sensors used to measure temperature by correlating the resistance of
the RTD element with temperature. Most RTD elements consist of a length of
fine coiled wire wrapped around a ceramic or glass core. The RTD element is
made from a pure material which has a predictable change in resistance as the
temperature changes. It is this predictable change that is used to determine
temperature.


CONTENTS


1. AMMONIA PLANT


2. UREA PLANT


3. STEAM GENERATION PLANT (S.G.P)


4. CAPTIVE POWER PLANT (C.P.P)

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5. OFFSITE


6. CONCLUSION

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AMMONIA

PLANT









Ammonia plant is congregation of several processes working in co-ordination
with each other.

SECTION WISE DESCRIPTION:

1. AIR SEPARATION UNIT (A.S.U):

Introduction:

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A.S.U and N.W.U have been supplied by m/s HITACHI of JAPAN for Bathinda
fertilizer project.

TOTAL AIR SUPPLIED 1,40,000 Nm³/hr

PRESSURE 7 kg/cm²

OXYGEN PRODUCED 26,000 Nm³/hr

NITROGEN PRODUCED 58,000 Nm³/hr

 A.S.U can be operated when N.W.U is under shut down.
 Expansion turbine provides the necessary refrigeration for A.S.U &
N.W.U with both running during cooling down of the unit & one running
during normal operation.

PROCESS:

Feed air cooled in pre-coolers from 45ºC to 40ºC & further cooled to 5ºC
in chiller. Air is then passed through air dryers. After dryers, it enters the cool
box, some of the feed is even utilized in expansion turbine. Feed air then enters
the rectification section, which consists of upper, lower column & main
condenser in between. The lower column consists of Al containing sieve trays
and a bubble cap tray, located at bottom. O2 with about 40% purity is obtained
in lower column and gaseous and liquified N2 are obtained at the top & bottom
of lower column. The liquified air withdrawn from the bottom of lower column
passes through one of the alternately operating HC absorbers,finally liquid air
filters to remove contamination of HCs.

Then it is super cooled with waste N2 from upper column in liquid air
super cooler before being expanded to pressure of upper column. The impure N2
withdrawn from middle of lower column is fed to the upper column whereas the

liquid N2 withdrawn from the top of the lower column is supercooled in liq. N2
supercooler through an expansion valve. The rectification process continues &
liquified O2 of atleast 98% purity is obtained in the main condensor which is
evaporated there to form the pure O2 product & is withdrawn from the bottom
of upper column. Pure N2 is withdrawn from the top of the upper column with
purity of maximum 8 ppm. Apart of liq. O2 is continuously circulated by one of
two alternately operating liq. O2 pump from condensor to circulating absorbers
& liq. O2 filters to remove remaining traces of HCs. The waste N2 is withdrawn

16. 16
from middle part of the upper column & warmed in liq. air supercoolers & air
heat exchanger & extracted from cold box.

Cold required for liquification can be produced by either method:

a.) FREE EXPANSION : the gas is expanded at constant enthalpy in an
expansion valve. This method requires a h.p. to produce a large qty. of cold.

b.) EXPANSION WITH EXTERNAL WORK: in this process the gas is
expanded at constant entropy.
This is a better & cheaper expansion.

BEWARE:

ACETYLENE & HCs can prove explosive, so stopping & warming limits are
specified.

HYDROCARBON SOLUBILITY EXPLOSIVE
LIMIT

Methane in any proportion 5.4%
Ethane 2.5% 4.1%
Ethylene 3% 2.9%
Propane 6% 2.3%

2.GASIFICATION:

It is the process in which partial oxidation of HCs takes place in the
presence of oxygen and steam. The reaction involved are :

CnHm + n/2 O2 ------------------------ nCO + m/2 H2
CnHm + nH2O ------------------------ nCO + (m+n) H2

Partial oxidation is preferred to complete oxidation because it is due to


partial oxidation that we get more amount of hydrogen, which is very expensive
and desired gas. If complete oxidation been done, we get water and carbon
dioxide

which are undesired products and even our motive of getting nitrogen is not
achieved.
This process of gasification can be divided into following parts namely:

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a.) HEATING AND CRACKING:

Heating is done in the pre heaters and heat exchangers where as the
cracking process takes place in the reactor where the HCs leaving the atomiser
to pre-heater temperature are mixed with oxygen and 40 K steam. Prior to
combustion they are heated and vaporized by back radiation of flame and the hot
reactor wall, the reactor walls have a refractory lining. Cracking of HCs to C,
methane and HC radicals take place in the reactor.

b.) REACTION PHASE:

On achieving of the ignition temperature HCs react with oxygen resulting
in an exothermic reaction:

Cn Hm + (n + m/4) O2 ---------------- nCO2 + m/4

As equilibrium is far to right practically, all available oxygen is consumed
in this phase. The rest of HCs which have not been oxidized react with
combustion product & steam resulting in an endothermic reaction:

Cn Hm + nCO2 ------------------------- 2nCO + m/2 H2
CnHm + nH2O ------------------------- nCO + (m/2 + nH2)

To prevent excessive local temp. It is essential that eqn. 3 to 5 are
intimately mixed so that exo & endo reactions are balanced. In this way the
complex reactions are brought in thermal equilibrium resulting in measured
temp. of about 1573 K to 1673 K.

c.) SOAKING PHASE:

This takes place in rest of reactor where gas is still at higher temp. The gas
composition changes slightly owing to secondary reaction of methane, carbon &
shift reaction. Methane content is decreased as under:

CH4 + H2O ----------------------------------- CO + 3H2
CH4 + CO2 ----------------------------------- 2CO + 2H2

The reaction rate is slow than expected at equilibrium, therefore methane
content is also low.
If sufficient residence time is provided, the C formed can also disappear
following:

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C + CO2 ------------------------------------- 2CO
C + H2O ------------------------------------- CO + H2

2.CARBON RECOVERY UNIT:

Carbon recovery has been designed for concentration of 1.5-3.0%. A
constant concentration in carbon slurry is essential for smooth operating of
palletizing machines which is ensured by operating the plant at constant
capacity.

PRINCIPLE OF WORKING: size enlargement phenomena

A phenomena in which small particles are gathered into large masses in
which original particles can still be identified. This is carried out rotary drum
agglomerators with the help of agglomeration by tumbling method. During ball
growth there is balance between destructive forces produced between the charge
& cohesive forces holding the pellets together. Pellet strength must be sufficient
to withstand these destructive forces. Carbon particles in water suspension are
agglomerated & separated from the C slurry with addition of heavy oil which
preferentially wets the carbon particles & is immiscible in water. Heavy oil
deposits on the larger surface of carbon particles & individual carbon particles
agglomerate to form heavier flakes.

Under appreciable agitation s.a. rotation of palletizing machines, the flakes
are converted to small particles of about 10mm diameter. The palletizing
machines are cylindrical vessels of about 13m height. At the level of carbon
slurry & heavy oil inlet a three legged agitator is provided to disperse the up
coming slurry. Above this agitator a cylindrical rotor is provided which rotates
the rising water & pallets core flinging them to the vessel where by collision &
rotation the spherical pallets are formed.

3.RECTISOL-1 or DESULPHURISATION:

The crude gas from C scrubber (in gasification section) enters rectisol-1 at
48 kg pressure & temp. 45ºC containing 97% H2S, 04% CO2. The gas is
saturated with water. The entrained condensate is separated in scrubber effluent
drum FA-202 & 204 & send to collecting pipe in the C recovery unit, through
AFA-113. At the bottom of DA-201, crude gas is cooled with small amount of
cold methanol to remove mainly cynogen compounds. The loaded methanol is
sent to reflux drum.

The gas reaches the upper portion of DA-201 via chimney tray & here the H2S
& all other organic S compounds are removed selectively by cold regenerated

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methanol from N2 stripping stage of CO2 regenerated down to total S content of
.4 p.p.m. The old desulphurised gas leaves H2S absorber at -28ºC through a
demister installed at the top of the absorbed thus preventing entrained methanol
droplets in the gas. The gas is used for H2S removal section at 35º C & 45 kg
pressure.

4.SHIFT CONVERSION:

In shift conversion section,S free gas reacts with steam to form H2 and
CO2.

CO + H2O ----------- H2 + CO2

Excess steam is used to prevent C deposits and to procure higher rate of
conversion. There is a limit of excess steam supplied because too much excess
steam reduces the content time between gasses and the catalyst which further
reduces the rate of conversion. The reaction is exothermic,then equilibrium is
favoured towards H2 formation by low temp but rate constant by high
temperature.

CATALYST USED ARE:

1. iron oxide
2. cobalt molybdenum
3. copper zinc
4. iron chromium(it is used at NFL in temp. ranging between 350ºC and 500ºC)

5.RECTISOL-2 or DE-CARBONATION:

122576m³/hr of converted GSA at 45ºC & 42.5 atm containing 33.72%
carbon dioxide enters the section from the shift conversion section. Since the gas
is water saturated, entrained condensate is separated in separators FA-404 &
406. The gas is then cooled in three steps:

1. From 45ºC to 27ºC in heat exchanger, EA-401 A with synthesi gas from
nitrogen wash unit.
2. From 27ºC to -16ºC in heat exchanger, EA-401 B with synthesis gas from
N.W.U.
3. From -16ºC to -25ºC in ammonia chiller EA-402.

In order to avoid formation of ice below freezing point. Methane is
injected in covertor gas steam before it enters EA-401 B. The condensate from

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EA-401 B is passed on to CO2 flash column DA-205 for stripping off CO2
before being sent to

methanol water rectifier DA-204. The converted gas at -25ºC & 404 kg/cm² gas
enters the CO2 absorber bottom where all CO2 is removed from the gas by
washing with cold regenerated methanol from the sripping stage of CO2
regenerator fed at the tray & finally pure methanol from hot regenerator at the
top of the tower.

6.NITROGEN WASH UNIT:

Decarbonated gas coming to N.W.U from rectisol 2
nd
, decarbonation at
39.5kg/cm² & 55ºC containing 5.21%CO, 50% methane, 93.62% of hydrogen,
67% nitrogen & argon CO & methane are undesired components in synthesis as
ther act as catalyst poison & inert respectively. They are so removed from
gaseous mixture by liquid nitrogen wash. Hydrogen boils at considerably lower
temp. than other impurities which are removed by fractional distillation. B.P of
hydrogen is -249.4ºC nitrogen at -195.8ºC, carbon monoxide at -191.5ºC &
methane at -161.5ºC. The methanol content from decarbonated gas is removed
by passing through molecular sieve in absorbers beds. After CO2 & methanol
removal in absorbers, gases enter the cooled box, where washing with liquid
nitrogen from A.S.U is done. Finally purified gas slightly rich in nitrogen, leaves
from the top of the tower.

7.AMMONIA SYNTHESIS:

Make up gas coming from N.W.U is compressed to around 220kg/cm²
press by synthesis compressor. Upto 3 stages of compressor make up gas is
compressed, while the suction of 4
th
stage or the recycle stage, it is mixed with
recycled gas coming from the synthesis section (3
rd
and 4
th
stages are housed in a
single barrel). Recycled gas goes to ammonia converter, radial type, consisting
of 2 beds charged with reduced iron-oxide catalyst.

N2 + 3 H2 -------------------------------- 2 NH3 + heat

Is a reversible reaction. Ammonia produced along with unreacted gases leaves
the convertor, it is first cooled in economizer, then in synthesis hot gas
exchanger. Ammonia is then liquified & separated, gases from separator are
even recycled. Cooling system of ammonia chiller is equipped with refrigeration
compressor. Thus the ammonia product being formed is sent to urea plant for
storage.

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Urea
Plant

22. 22










As we know that our ultimate aim is to maufacture urea which is achieved by
the reaction of ammonia with carbon dioxide. We get ammonia manufactured
from ammonia plant which has to combine with carbon dioxide to form
carbamate which further changes to the urea. Therefore the manufacture of urea
includes following main sections:

1. synthesis section

2. decomposition section

3. crystallization & prilling section

1.SYNTHESIS SECTION:

This is the section in which ammonia is made to react with carbon dioxide
to give ammonium carbamate which further changes to urea with removal of
water. The two reactions involved finally result into an exothermic reaction. The
conversion of ammonium carbamate to urea depends upon:

a. reaction temperature & pressure
b. molecula ratio of ammonia/carbon dioxide, H2O/CO2 of the feed reactants
c. residence time

2NH3 + CO2 ------------------------------- NH2COONH4
(ammonia carbonate)

NH4COONH4 ---------------------------- NH2CONH2 + H2O
(urea)

The reactions are reversible. The principle variables affecting the reaction are
temperature, pressure, feed composition and reaction time.

2.DECOMPOSITION SECTION:

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MITSUI TOATSU TOTAL RECYCLE C IMPROVED PROCESS is a
conventional process i.e. the process where decomposition is effected by
lowering in press. In successive stages followed by indirect heating whereas the
process where decomposition takes place by lowering the partial pressure of
either NH3 or CO2 followed by indirect heating called STRIPPING PROCESS.

NH2COONH4 --------------- CO2 + 2NH3


Decomposition is usually achieved at temperature of 120ºC to 165ºC.
Decreasing pressure favours decomposition,as does increasing temperature.

3.RECOVERY SECTION:

The gas from the gas separator, goes to off gas condensor, cooled down to
61ºC by C.W. enter in the bottom of off gas absorber O.G.A. consists of 2
packed beds. Some amount of ammonia and carbon dioxide are absorbed and
condensed in the lower packed bed by recycle solution which is cooled down in
O.G. cooler. In absorbed packed bed, absorbed and condensed are the residual
ammonia and carbon dioxide completely by the condensed solution in O.G.
Condensor after being cooled down at gas final cooler. The air from top of
O.G.A. is blown to gas separator by off gas recycle blower after fresh air being
added at suction and pressure is controlled at the discharge.

It is not practical to compress the ammonia-carbon dioxide mixture &
return this to urea synthesis reactor. Compression causes the recombination
ammonia and carbon dioxide to solid ammonium carbonate and clogging the
compressor. The method of recycling the unreacted gas can be :

a. separate and recycle as gas
recycle in solution and slurry form

4.CRYSTALLIZATION AND PRILLING SECTION:

The urea solution leaving the de composer is vacuum crystallized and urea
crystals are separated by centrifuge. To use efficiency in the heat of
crystallization and to evaporate water at lower temperature, vacuum
crystallization is often used crystals formed in the vacuum crystallizer are
centrifuged and then dried to less than 0.33% moisture by hot air. To keep the
bluret content about 0.1% in crystals urea, a certain amount of mother liquor
which contains almost all the bluret originally present is recycled to the recovery
section as the absorbent liquid for carbon dioxide and ammonia.

24. 24

NH2CONHCONH2 + NH3 ---------------------------- 2NH2CONH2
(biuret) (urea)

Dry crystals are conveyed to the top of the prilling tower passing through
fluiding dryer. There, the crystals are melted in a specially designed steam
heated melted. The molten urea flows through distributors, and thus it is formed
into droplets.






Steam
generation
plant

25. 25
(S.G.P










Steam generation plant is mainly installed for production of steam and then
distributed to various parts of the plant. Here this section of plant installed in
national fertilizers limited, bathinda unit produces and supplies steam at 100
kg/cm² pressure and nearly 480ºC temperature to ammonia plant.

In today’ s world steam has gained importance in industries. It may be
used for power processors and heating purposes as well.

Why and where steam is required……????

As nearly 6-7 tones of steam is required to produce 1 ton of ammonia.
This is used:

 for driving the turbo-compressor
 as process steam for various reaction
 for heating purpose

High pressure turbines are being used where high pressure and temp. is to
be maintained so SGP section plays an important role for maintaining the said
condition.

There are three boilers (VU-40 type supplied by M/S BHEL) of 150 ton/hr
capacity. These boilers are Water Tube Boilers i.e. water is inside the tubes and
hot air surrounds it when coal is burnt, this makes the water in the tubes boil and

26. 26
steam formation takes place. In the beginning coal is burnt with fuel oil to get
desired temperature.

BENEFITS OF STEAM:

 It is colorless, odourless and tasteless.
 Very economical.
 Non-polluting.
 Can be used as heat exchanger.
 It can be easily distributed to various sections of plant.












FUELS USED:

COAL:

To obtain steam of desired temperature and pressure, coal is burned to
give major source of heat. Initially coal is stored at Coal Handling Plant brought
from coal sites. It is this section of plant where coal is crushed by crushers in
order to make small pieces of coal, then after crushing it the coal pieces rare
passed through heavy electromagnet where iron is separated from coal if
present. Coal is then sent to bunkers from where it goes to Grinding mill.
Grinding mill is grinding coal into powder form.

Conveyor belts are being used in the whole plant for transportation of
coal. The powder form of coal is sent to the boilers through pump as pump sucks
the coal from grinding mills and throws it into the boiler for combustion.

» Coal pulverizing in boiler:

Coal is pulverized before firing for achieving a stable and efficient
combustion. Many types of pulverizers are used in the boiler by different
designers. Pulverizing coal is the most efficient way of using coal in a steam

27. 27
generator. The coal is grind so that about 70% will pass through 200 mesh
(0.0075mm) and 99% will pass through 50 mesh (0.300mm). Pulverized coal
boiler can be easily adapted for other fields like gas if required later without
much difficulty.

»The purpose of pulverizing in a coal fired boiler:

 To supply pulverized coal to the boiler.
 Transport the pulverized coal from the pulveriser to the boiler in the boiler.
 To remove moisture in coal to an acceptable level for firing in the boiler.
 To remove high density in organics from coal during pulveriser.
 To classify coal particles to the required level of fineness, normally 70%
through 200 mesh and less than 2% on 50 mesh.

FUEL OIL:

As the boilers are designed to wok on both coal as well as Fuel oil so fuel
oil can also be pumped to Boiler for combustion.

Generally coal alone is not burnt initially but fuel oil (LSHS) is mixed
coal and then sent to the furnace for combustion in order to get desired
temperature.



WATER AND STEAM SYSTEM:

As the steam being used should be free from impurities like minerals,
silica, oxygen, iron, etc in order to ensure safe and efficient working of steam
turbines and boilers. For this purpose raw water is physically and chemically
treated and finally supplied to steam generation plant from ammonia plant. This
water is called boiler feed water which is further heated to 240ºC by the flue
gases and taken to steam drum. Steam drum acts as strong tank and also
separates water from the steam at 315ºC and 106kg/cm². Pressure water then
enters the ring heater formed at the bottom of outside the furnace and rises by
gravity through water wall tubes on all the four sides, takes heat from furnace
and enters steam drum as a mixture of steam and water.

FLUE GAS SYSTEM:

28. 28
The products of combustion in the furnace consists of carbon dioxide,
nitrogen, ash, oxygen and sulphur dioxide. After leaving the furnace the heat of
these gases called flue gases, is utilised at various levels.

First the steam from the steam drum is heated in two super heaters to get
the required temp. of 495ºC and then feed water in bank tubes is also heated and
the gases leave the bank tubes at around 497ºC. next the heat is utilized to heat
feed water in the ECONOMISER and gases are cooled down to 320ºC. these
gases are further cooled down to 150ºC in ROTARY AIR HEATER where the
air is required for combustion and conveying the coal is heated up. Temperature
is not reduced further because at lower temp. oxides of sulphur present in flue
gases are converted to ACID which damages the down steam equipments. These
gases then pass through ELECTROSTATIC PRECIPITATOR (E.S.P) where ash
is removed.

29. 29
Captive
Power
Plant
(C.P.P)












NFL has set a Captive Power Plant (C.P.P) at there complex at Bathinda, to
ensure availability of stable, uninterrupted power and steam to the ammonia and
urea plant. This will minimize the tripping of the fertilizer plant due to transit
voltage dips and power cuts.

Since inception, Bathinda unit was drawing electric power from Punjab
State Electricity Board (PSEB). Electricity is the main driving force after steam
in the plant, being used for moving auxiliary equipments. The unit requires
27MW of power per hour when running at full load. There are two 15MW
turbo-generators to generate power. Under normal running conditions of the

30. 30
plant and healthiness of the PSEB grid, we generally run in synchronism with
the grid merely drawing the power corresponding to the minimum charges to be
paid to State Electricity Board. In case of any disturbance in the grid, our system
gets isolated from the grid automatically. With both generators running, we are
able to feed power to the whole plant, thus production is not affected. In case
only one turbo-generators is in line and grid cuts-off, urea plant is cut-off
automatically to balance the load with one generator. As soon as the grid
becomes stable, the generators are again synchronized with it. The power
generation of each generator can be varied with 2 MW to 15MW maximum,
provision exists to run the generator on 10% extra load continuously for one
hour only.

Operation of C.P.P is based upon microprocessor based computerized
instrumentation which allows automatic operation, start up, shut down of the
whole or part of the plant. It allows controlling process variables like flow,
pressure, temperature, power factor, voltage, frequency, etc. There is operator
interface unit (I.O.U) like t.v screen on which various parameters can be
displayed and controlled.

NEED FOR C.P.P:

It was thought to install a captive power plant in which electric power for
our requirement shall be generated in a coal fired boiler. The benefits envisaged
were:

1. Any disturbance in the PSEB grid used to trip the whole plant a lot of money
was lost, due to this as each re-start up cost around 40-50 lacs rupees. Moreover,
frequency trippings had an ill–effect on machines and equipments extending the
re-start up period.

2. Three boilers of 150 T/hr steam capacity were initially installed in S.G.P to
keep 2 boilers running and 1 stand-by as designed steam requirements was less
than 300 T/hr. But in actual operation steam requirement was more and all three
boilers had to be run and there was no breathing time for their maintanence. As

new boiler was to be installed for C.P.P, its capacity was so designed that it
could export around 60 ton of steam for process requirement so that only 2
boilers of S.G.P would be run keeping the 3
rd
as stand-by.

The functioning of C.P.P can be divided into parts:

BOILER:

31. 31
Boiler has been supplied by M/S MITSUI ENGINEERING AND SHIP
BUILDING CORPORATION OF JAPAN. It has a capacity to produce
maximum230 ton/hr of steam at 105 kg/cm² pressure and 495ºC temp.. 150 T/hr
steam is used for power generation if both generators are running at 15 MW
each. Around 60 ton steam per hour is drawn for process use and joins with the
S.G.P steam header. Main difference between two boilers are :

 S.G.P boiler is tangentially fired where as C.P.P boiler is front fired with 6
coal burners and 6 oil gun fixed inside the coal housing.
 S.G.P boiler can be loaded upto 30% load with oil firing only where as
C.P.P boiler can be fully loaded with oil alone.
 height of combustible zone in C.P.P boiler is more and it has residence time
of 1.5 sec where S.G.P boiler has 1.0 sec.
 due to more resistance time and better polarization the efficiency of C.P.P
boiler is about 4% higher.
 boiler feed water required for steam generation can be fully generated of
C.P.P itself.

TURBO-GENERATORS:

CPP is having two number turbo-generators of capacity 15 MW each.
These are totally enclosed self ventilated type with two lateral airs to water
coolers for cooling. The alternators are able to bear 10% overload for one hour
with an increase in temperature of 10ºC while maintaining the voltage as near as
possible to the rated one. The exactation is compound and brushless with exciter
rotor and rectifier mounted on the extended main shaft on non driving end. The
excitation is controlled automatically with automatic voltage regulator and a
PLC controller. In case of any distribution in grid, our system gets isolated from
the grid automatically. With both generators running, we are able to feed power
to the hole plant, thus production is not affected. In case only one TG is in line
and grid cuts off, urea plant is cut off automatically to balance the load with one
generator. As soon as the grid becomes stable, the generator are again
synchronized with it.


TURBINE

The turbine used is supplied by M/S SGP of AUSTRALIA. It is
condensing cum extraction turbine designed as single casing reaction turbine
with single control stage and high pressure (HP), mild pressure (MP), low
pressure (LP) reaction parts.

32. 32
The turbine is fed with high pressure steam at 100 kg from the boiler and
flows through various control valves for normal and emergency operation. It
gets high velocity fixed diffusers thus rotating the turbine. The enthalpy of the
steam is utilized in steps. The exhaust steam from the turbine is condensed in a
condenser maintained under vacuum to extract maximum steam enthalpy. The
output of the turbine depend upon the flow of the steam and heat difference that
is on condition of the steam at main steam valve and the pressure at the turbine
outlet or condenser pressure. The turbine is connecting to the generator through
reducing gears.

The exhaust steam is condensed in a condenser using cooling water. The
resulting condensate can be fed back to LP heater but it is normally sent to the
polishing water plant.

Various bleeds from the turbine are utilized for heating purpose. HP1 and
HP2 are used for heating boiler feed water in HP1 and HP2 heater. Feed water
bleeds is used for heating the feed water tank and LP bleed is used for heating
the polish water make up to feed water tank.

A lubrication system is also there to lubricate the various bearings of
turbine, gears and generator. Normally the oil pump driven by the turbine shaft
supplies oil but has been provided for slow cooling of turbine rotor.

Description:

Making simmering Graz Panker, Austria

Type Multifunctions (28 stages)

RPM 6789 at 50 Hz

Critical speed 3200-3600 RPM





FUEL COAL SYSTEM:

The purpose of fuel coal system is to pulverize coal to dry coal and to
convey the pulverized coal from ball tube mill to burners by primary air for coal
firing.

33. 33

Fuel coal system consists of three system:

1. coal supply system
2. primary air system
3. seal sir system

COAL SUPPLY SYSTEM:

COAL COAL CRUSHERS
BALLTUBE
------ ------ ------
BUNKER FEEDER DRYER MILL


Primary air system:

The primary air system performs two functions. It provides the proper
amount of air required to convey the pulverized coal to the burners and the heat
necessary to dry coal so it can be pulverized and burned efficiently.

Seal air system:

The seal air is distributed to the component by the sealing of the mill by
the sealing air fan. The sealing air fan takes suction from silencer and discharges
it to a commom header. The controller for each mill system provides a constant
diferential pressure to protect against coal leaking into the bearings and seals.

Crush dryer system:

Crush dryer performs the crushing function. Metered coal from the
feeders blends with a properly heated amount of air from the primary air fan and
enters the crush dryer. Rotating hammers drive the incoming coal against a
breaker plate and adjustable crusher block, increasing the surface area of the
coal and mixing it with the incoming pre heated air.



Forced draft fan:

The forced draft fan supply the proper amount of secondary air required to
support the combustible of the fuel delivered to the boiler.

34. 34

Induced draft fan:

The induced draft fans control the furnace draft by drawing the gases of
combustion through the boiler, regenerative air heater, delivering them to the
stacks. Thus the FD fan provides combustion air for the furnace while the ID fan
removes flue gases from furnace through chimney.

Power generation:

There are two 15 MW turbine generator sets to generate at 11 kV which is
fed into 132kV bus of PSEB and again distribution network.

35. 35









DISTRIBUTED

CONTROL

SYSTEM

36. 36









DEFINATION :-

A Distributed Control System (DCS) is a control system method that is
spread, or distributed, among several different unit processes. Controller
elements are not central in location but are dispersed throughout the system with
each component sub-system controlled by one or more controllers. The entire
system of controllers is connected by a network for communication and
monitoring.

It is generally, since the 1970’ s, digital and normally consists of field
instruments, connected via wiring to computer buses or electrical buses to
multiplexer/de-multiplexers and A/D’ s or analog to digital and finally the
Human-Machine Interface (HMI) or control consoles. A DCS is a process
control system that uses a network to interconnect sensors, controllers, operator
terminals and actuators. A DCS typically contains one or more computers for
control and mostly use both proprietary inter-connections and protocols for
communications.

DCS is a very broad term that describes solutions across a large variety of
industries, including:

 Electrical power grids and electrical generation plants.
 Environmental control systems
 Traffic signals.
 Water management systems.
 Refining and chemical plants.
 Pharmaceutical manufacturing.
 Water management systems.
 Refining and chemical plants.
 Pharmaceutical manufacturing.

37. 37










Architecture of DCS

38. 38











Slave Module Functions

Slave module functions include.

 Range and mode selection.
 Voltage threshold selection for digital I/O.
 Response time selection.
 Signal buffering.
 Signal conditioning.
 Signal isolation.
 Noise rejection.
 Analog to digital and digital to analog conversion.
 Cold junction compensation for thermocouples.


C-NET:

C-NET is a unidirectional, high speed serial data network that operates at a
10 megahertz communication rate. It supports a central network with up to 250
system NODE connections.

The NIS allows any node to communicate with other node within the
symphony
system.,it to be interface with the nict module over dedicated expander bus.

The NICT module receives command from the host computer,execute
it,then reply. The NICT module is single printed circuit board which contains
microprocessor. Based communication circuitry that enable to
directcommunication with its NIS module, To direct communicate with MPI
module.

39. 39
The IMMPI01 Multifunction Processor Interface module handles the I/O
interface between the host computer and NICT module. The IMMPI01 module
supports either SCSI parallel port at rates 4M byte/s or RS-232-C serial link at
the rates up to 19.2 Kilobaud/s.








NETWORK 90 SYSTEM OVERVIEW

Network 90 plant control system is a distributed control system. Using a
series of integrated circuit, the NETWORK 90 lets the operated monitor and
control the process variable such as rate, temperature, pressure etc. according to
control configuration that engineer set for the plant.

The major elements of system are:

1. Process Control Unit (PCU)
2. Operated Interface Unit (OIU).
3. Computer Interface Unit (CIU).
4. Management Command System Unit.
5. Plant loop to loop gateway.

From these only PCU and OIU are used in NFL Bathinda rest is not being used
in this plant. The communication loop (PCL) ties all the nodes together. The
PCL enable the communication among the nodes for:

 Sharing of control variable among the modules in different PCU’ s.
 Monitoring operation of the control scheme in the PCU’ s with an OIU.
 Controlling and process from an OIU.
 Configuring and maintaining the control scheme of a PCU from an OIU.
 Monitoring the status of PCU equipment from an OIU.

NETWORK 90 SYSTEM NODES:

1. Process Control Unit (PCU): NETWORK 90 control and process modules
are mounted in standard modules Monitoring Unit (MMU) which are

40. 40
mounted in PCU system cabinets. In the cabinet, power supplies and
termination unit are also installed.

2. Operator Interface Unit (OIU): OIU is a CRT based console, which
provides access to entire NETWORK 90 system for plant operation,
control engineering and system trouble shooting.

3. Engineering Work Station (EWS): Engineering work station is an
integrated hardware/software package that provides remote access to
NETWORK 90 system. EWS allows communication with entire
NETWORK 90 system through the plant communication loop. With EWS
operator engineer can

design, configure, monitor document or troubleshoot NETWORK 90 process
activities as designed.


HARDWARE:
 personal computer
 640 K RAM
 20MB hard disk
 14” CRT with keyboard
 Pen plotter

FUNCTIONS:
 design and configuration with process logic Control
drawing.
 Symbol of control logic
 CAD functions for configuration.
 Monitor & tune of n/w 90 module.
 Store & load module configuration.

41. 41
















Advantages of DCS

• Compact system
• Can share data over the network
• Online programming of the controllers
• Hot redundancy of controllers, network and power supplies, thereby
making the system more reliable
• System is highly rugged and maintenance free
• Trouble shooting is simple and easy due to availability of trends, operator
action logs with time stamping along with user names
• Overall system is cheap for large plants
• Different security levels for different users are available. So same machine
can be used for different functions by different users without effecting
each others work
• Web monitoring is possible of graphic and trend windows on a general-
purpose WWW browser by converting HIS files into HTML files and java
applets. Thus making remote monitoring in offices far from the
instrument is possible

42. 42



















OFFSITE


1. It is often referred to OGP meaning offsite group of plants.

DESCRIPTION OF PLANTS:

1.RAW WATER PLANT (R.W.P):

The raw water procured from Bathinda canal is at first stored in reservoir.
The procured water has impurities like:

a. SETTABLE: e.g. mud,clay,sand which are settled in reservoirs.

b. UNSETTABLE: these impurities can be either dissolved or suspended.
The suspended impurities can be cleaned by method of flocculation in
which agglomerates are formed, further water is purified in sand filters
installed.

2.DE-MINERALISED PLANT (D.M. PLANT):

Basic principle of working : ION EXCHANGE

43. 43

At first come across cation unit in which elements like Ca, Mg, Na are removed.
As a result of which HCI & carbon dioxide are formed & even small quantity of
carbonates which are removed by DEGASING. In degassing water is sprayed
from up & air is supplied from bottom as a result of which gases like carbon
dioxide are removed. Further impurities viz. chlorides, sulphates, silicates are
removed by passing water ahead through primary mixed bed which contains
both cationic A.W.A anionic resins which are regenerated after being exhausted
by acid & alkali respectively. Then further water is stored in D.M water tanks
passed through secondary mixed bed & finally we get our required polish water.

3.COOLING TOWERS :

These are water towers installed to remove the unwanted heat which as a
result increases the efficiency of the plants even individually.
There are basically three C.Ts:

C.T-1

In which all the cooling for ammonia plant is done exclusively.


C.T-2

For treating water from urea plant

C.T-3

For water from prilling tower.


4.COMPRESSOR HOUSES:

They have been used to run the whole system under numatic control. In
this the compressor sucks in air which is then dried with the help of dryers to
remove the moisture content.

Four lubricating pumps have been installed because we don’ t want any
presence of air which can lead to corrosion.

Teflon rings are used to have least friction possible. Dew point is
maintained at approximately -30º, its good to achieve a bigger negative value.
E.g. -55º but not vice-versa.

44. 44


6. EFFLUENT TREATMENT PLANT (E.T.P):

There are 4 basic types of wastes namely:

a.chemical waste

b.acidic waste

c.alkali waste

d.sewage waste

These wastes are all put in a sump, from were they pass through innumerable
process namely aeration, nitrification (to produce bacteria need for
decomposition) then denitrification & many more. Therefore at last we achieve a
stage where all effluents are removed & the treated water is stored safely in 3
reservoirs , again ready for reuse.










CONCLUSION


After doing my training at NATIONAL FERTILISERS LIMITED,
BATHINDA. I felt the importance of training in industry and its practical
application. When I was studying the theory of different concepts I was thinking
how all these would be implemented but after training I learnt that how all these
could be put in use. It was the result of training only that I got to see the objects
in real and practical use, which I only read.

During my training at NATIONAL FERTILISERS LIMITED,
BATHINDA. I got a chance to expose myself to industry culture and work
environment. In other words these two months of training at N.F.L. were a real

45. 45
learning experience. All the way these happened due to co-operation of staff and
management who helped me in gaining knowledge about whatever I have today
about industry. In the end, I would like to conclude that the training is an
essential part of the education program. We should always persue for the
theoretical as well as practical knowledge, both of which are must for the
foundation of the high building.



“ SAFETY COMES IN CANS”


I CAN, YOU CAN, WE CAN



















REPORT ON
INDUSTRIAL TRAINING
AT
NATIONAL FERTILIZERS LIMITED
(AN ISO-14001 UNIT)
BATHINDA

46. 46




SUBMITTED BY:
KAMALPREET KAUR
ROLL NO. 11402039
E.C.E

PUNJABI UNIVERSITY
PATIALA

(10june 2016-15 july 2016)